Filtration is used to reduce certain particulates and/or vapour phase constituents of tobacco smoke inhaled during smoking.
Smoking article filters may include porous carbon materials to adsorb certain smoke constituents, typically by physisorption. Such porous carbon materials can be made from the carbonized form of many different naturally occurring organic materials. Alternatively, synthetic carbons can be used, such as resins prepared by polycondensation reactions.
It can be important that the filtration of particulates and/or vapour phase constituents of tobacco smoke is achieved selectively, for instance without removing significant levels of other components.